The city plans to target increasingly popular cycling areas in midtown as well as dangerous borough streets for safety improvements while new data shows biking rates citywide leveling off.

Following a remarkable 320-percent growth in bicycling over the past two decades, the rate of new city riders over the last two years has grown at a slower pace, according to the latest “Cycling in the City” report. The cycling count, a comprehensive look at where the more than 800,000 New Yorkers who bike regularly travel, is to be released by the city’s Department of Transportation on Wednesday.

Certain areas, such as midtown and points farther north in Manhattan, have seen a steady influx in biking, drawing the focus of planners.

“We’re seeing growth there sort of jump in leaps and bounds,” said Sean Quinn, senior director at the Office of Bicycle and Pedestrian Programs at the city’s DOT, who credited the growth to the robust bike infrastructure on Manhattan avenues as well as to Citi Bike.

Between 2012 and 2017, there was a 55 percent increase in the number of cyclists riding north or south past Manhattan’s 50th Street, a jump from 18,931 five years ago to 29,364 last year. Similar increases were experienced over that same time across 86th Street, too.

“We had some pretty high-profile fatalities in midtown south of 60th Street. There were four fatalities with cyclists going crosstown, not on protected lanes,” Quinn said. “That’s really the focus of our efforts this year to improve the crosstown network. And then, generally, we’re looking across the city at problematic locations.”

At the same time, the number of weekday cyclists over the city’s four East River bridges dipped slightly — from 22,626 in 2016 to 22,408 last year. While the drop is small, 2017 was the first down year for bridge biking in 11 years.

Overall cycling growth under the first three years of Mayor Bill de Blasio’s administration showed smaller gains: a 9 percent increase in daily cycling trips between 2014 and 2016, according to the most recent data available in the report. During the three years directly prior, between 2011 and 2013, there was a 33.8 percent jump.

Under this administration, the DOT has installed almost 330 miles of bike lanes, including more than 68 protected lane miles, which typically use parked cars to separate cyclists from traffic. While advocates are pleased with the projects, they believe the city should be rolling them out much more quickly. They criticize the sometimes lengthy community board process through which the city seeks neighborhood approval for new bike lanes and safety improvements.

The protected lanes in Manhattan’s 20s appear to be moving forward mostly without conflict from the affected communities. However, Community Board 5, which encompasses the streets between Lexington and Eighth avenues, tabled a vote on the projects last month, asking for more information from the city.

Wally Rubin, the district manager at the community board, said the board has not yet formalized a stance and that it plans to review the project again at the transportation committee meeting next Monday.

“Cycling in most neighborhoods is still a very high-stress activity,” said Paul Steely White, executive director of the advocacy group Transportation Alternatives. “And so really, the next step for Mayor de Blasio to make good on his promise to double ridership under his tenure is to dramatically expand the network of protected lanes — lanes that do a much better job of insulating cyclists from reckless drivers and really get regular people riding, not just the uniquely intrepid.”

Owen Gutfreund, associate professor of urban affairs and planning at Hunter College, said the city has a way to go in making sure drivers and pedestrians “respect” the bicycle lanes. The same goes for ensuring cyclists don’t flout traffic laws, he added.

“Mayor de Blasio has not yet put the energy into (bike infrastructure) that his predecessor did. He’s continuing the effort, not driving it forward in the way I would have hoped,” Gutfreund said.

But he reasoned that “if we continue to provide additional cycling infrastructure, cycling use will continue to grow. That’s the bottom line.”